Propellant charge for devices used industrially

ABSTRACT

The present disclosure is directed to a propellant charge for industrial use which comprises a body of a propellant powder having a centrally disposed recess extending therethrough, said recess containing a percussion sensitive primer substance, said primer substance being housed in the recess in such a manner that the compacting of the primer substance remains below the value required for the ignition thereof upon a sudden unexpected compression of the propellant charge in the direction of the axis of the recess.

United States Patent 1 Marondel et a1.

PROPELLANT CHARGE FOR DEVICES USED INDUSTRIALLY Inventors: Giinther Marondel, Erlangen;

Heinz Gawlick, Furth; Werner Siegelin, Stein, all of Germany Assignee: Dynamlt Nobel AG, Troisdorf,

Germany Filed: Oct. 31, 1969 App]. No.: 872,809

Foreign Application Priority Data Oct. 26, 1968 Germany P 18 05 359.3

[1.8. CI 102/101, 102/45, l02/D1G. 1 Int. Cl ..F42b 1/00 Field of Search 102/101, 99, 39,

102/104, 105, DIG. 5; 89/7 [111 3,754,510 [451 Aug. 28, 1973 [56] References Cited UNITED STATES PATENTS 3,580,180 5/1971 Gawlick et al 102/45 Primary Examiner-Robert F. Stahl Attorney-Craig, Antonelli and Hill [57] ABSTRACT 9 Claims, 3 Drawing Figures PATENIEmusze ms 3.754.510

FIG. I

FIG. 3

8 l Q l 1 H INVENTORS GUNTHER MARONDEL HEINZ GAWLICK WERNER SIEGELIN d M-MLZJ MWM ATTORNEYS PROPELLANT CHARGE FOR DEVICES USED INDUSTRIALLY BACKGROUND OF THE INVENTION The present invention relates to a caseless propellant charge for devices used industrially for example, stud driving tools. According to the present invention, a body of propellant powder having preferably a central recess extending therethrough is provided with a percussion-sensitive primer mass disposed in said recess.

In order to avoid the splintering and rupturing effects observed in cartridges having a propellant or primer charge housed in a casing made for example, of a metal, which effects occur on the wall of the cartridge case, it is well known to employ caseless propellant charges wherein, in the zone of a preferably central recess of a formed or cast body made of a suitable propellant powder, a precussion-ignitable powder charge is provided.

SUMMARY OF THE INVENTION only, since various changes and modifications within the spirit and scope of the invention will become apparent .to those skilled in the art from this detailed description.

Pursuant to thepresent invention, it has been found that the abovementioned disadvantages may be elimi named and a much improved caseless propellant charge may be obtained by providing that the primer sub-v stance is accommodated in the recess of the propellant powder body in such a manner that the compacting (condensing) of the primer substance remains below the value required for the ignition thereof upon a sudden compression of the propellant charge in the direction of the axis of the recess. The compression is effected by the use of percussion energy which is customary in these devices and is at least approximately uniform over the entire cross section.

The fact that the desired high degree of safety against inadvertent ignition is obtained by constructing the propellant charge in accordance with the present invention can be seen unequivocally from the aspect that, for igniting the propellant charge, a necessary prerequisite is a device with a specific construction, namely a device wherein the receptacle, housing the propellant charge, and the firing or striker pin are of such a structure, or cooperate with each other in such a manner, that the primer substance by itself is compressed or compacted between the striker pin and a solid (fixed) abutment. The compression extends beyond that corresponding to the axial compression of the propellant charge by the percussion energy customary in this kind of device. Alternatively, the primer subs ance, in addition to the compression of the entire propellant charge effected by the percussion energy customary in the device, is also subjected toan additional compression or compacting, leading'up to and exceeding the value required for the ignition and thus resulting in ignition.

- However, in addition to the above, a high degree of safety against unintended ignition is also obtained by the fact that the forces occuring in the operation of these devices are substantiallygreater than those to which the propellant charge is exposed externally of the devices. External forcesmight include, for example, an inadvertent blow with a hammer on a propellant charge lying around the area, or inadvertently stepping on a dropped propellant charge, etc. Accordingly, the forces produced in the devices of the present invention are greater than required for safety reasons.

Advantageously, the recess of the propellant powder body is completely filled with the primer substance. This simplifies things, especially from a manufacturing point of view, since it is possible to prevent the primer substance from falling out, by applying a uniform, thin varnish coating on the end faces to seal the same. The complete filling of the recess of the propellant powder body with the primer substance is also advantageous insofar as it ensures, without any special measures, that the primer substance is always disposed in an even and uniform level over the entire cross section of the recess, even in the case of a very loose compaction, independent of the respective position of the propellant charge. Accordingly, the same conditions are created for ignition of the propellant charge over the entire cross section.

lncorrespondence with the respective requirements and in accordance with the materials employed for the propellant powder body as well as the primer substance, the minimum value of axial compression necessary for triggering the ignition can be selected to be a high value. In the interest of as great a safety margin as possible,this value is chosen to be very high, for example, at least 80 percent. Such a high degree of compression or a corresponding amount of compacting also produces the advantage that the mechanical abutment provided for the intended pure percussionignition is especially effective as an anvil, i.e., for utilizing the percussion energy for the ignition of the propellant charge.

Suitable for the percussion-sensitive primer substance are conventional materials or mixtures of said materials known for this purpose. However, according to the present invention, an intimate'mixture of tetrazene and nitrocellulose is preferably employed, which mixture can be varied or adjusted within very wide limits, by correspondingly dimensioning the percentage proportions of the two components, with respect to their percussion sensitivity. The percussion sensitivity,

as found by experimentation, is at least as large or larger than the percussion sensitivity of the indivudual components. This makes it possible, in an advantageous manner, to effectively adapt to the respective propellant employed, with respect to the percussion and ignition sensitivity of the primer substance. I

The propellant which canbe used in the present invention includes for example, non-gelatinized nitrocellulose which can be pressed into a highly compacted propellant powder body. The propellant powder body can also be made of a gelatinized propellant, for example gelatinized nitrocellulose, by the extrusion method; This has the advantageof being simple and inexpen' sive. The propellant powder body can also be a porous or a non-porous propellant cemented with an organic binder which leaves no residue upon deflagration.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only and thus are not limitative of the present invention and wherein:

FIG. 1 shows a propellant charge in an axial, sectional view;

FIG. 2 shows a device for igniting the propellant charge in the opened condition; and

FIG. 3 shows the device in the closed condition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, the propellant charge of FIG. 1 comprises the annular propellant powder body 1 which is cast or pressed (formed) from the propellant, or produced with the use of a conventional organic binder, for example an epoxy resin, which burns without leaving any residue. The primer substance 2 completely fills the annular inside cross section. In this connection, the ratio of compressibility of propellant to primer substance is about 1:10 to l:l,000. Thus, it can be seen that, upon a sudden axial compression of the propellant charge effected with the use of percussion energy which is customary when employing devices for industrial usage, for example when using stud driving tools, the primer substance experiences only a relatively minor compacting, which is not yet sufi'lcient for ignition. Therefore a further compacting of the primer substance is necessary. In order to prevent the primer substance from inadvertently dropping out of the propellant powder body, the powder foil 9, covering at least the inside cross-section, can be provided. It is also possible to varnish the end face with a suitable material which burns without leaving a residue.

Elements 3 and 4 of FIGS. 2 and 3 are parts of a stud driving tool which is not shown in detail, operating in accordance with the so-called thrust piston principle. The projection 6, which is adapted in its cross-sectional dimensions to the inside cross-section of the propellant powder ring 1 of a correspondingly dimensioned propellant charge of FIG. I, filled with primer substance 2, extends into the recess 5 of part 3. The recess 5, which serves as the support for the propellant charge is likewise adapted to the dimensions of the propellant charges being employed. Also, the cylindrical extention 7 of element 4 is dimensioned so that it is adapted to the dimensions of the propellant charges being employed, as well as to the dimensions of the recess 5. Accordingly, as seen in FIG. 3, when elements 3 and 4 are joined, the closed annular space 8 results, into which the propellant power bodyI-I of an inserted propellant charge is pressed whenat'h'e'zdevice is closed. After the primer substance 2 has been compressed to the minimum dimension between the front faces of the extension 7 and the projection 6 and thus has been highly compacted above the value required for ignition and accordingly has been ignited, the propellant powder body, after being ignited, is converted'into propellant gases of a high pressure required for the desired acceleration of one of the two elements.= i

What is climedis:

l. A caseless consumable propellant charge for industrial use which comprises a body of a propellant powder having a recess disposed through a substantial portion of said body, said recess being substantially filled with a percussion-sensitive primer substance, said primer substance having a compressibility greater than the compressibility of the body of said propellant powder whereby a sudden unexpected compression of the propellant charge in the direction of the axis of the recess, and the resultant compacting of the primer substance remains below that value of compression required for ignition thereof, the ratio of the compressibility of said propellant powder to said primer substance being about 1:10 to 121,000 and the compression value required for ignition is reached only after an axial compression of said primer substance of at least about percent.

2. The propellant charge of claim 1, whrein a powder foil covers the recess to prevent the primer substance from inadvertently dropping out of the propellant powder body.

3. The propellant charge of claim 1, wherein a varnish coating is-provided at the end face of the charge.

4. The propellant charge according to claim I, wherein the percussion-sensitive primer substance contains an intimate mixture of tetrazene and nitrocellulose.

5. The propellant charge of claim 1, wherein the propellant powder body contains non-gelantinized, highly compacted nitrocellulose.

6. The propellant charge according to claim 1, wherein the propellant powder body contains an extruded a gelantinized propellant.

7. The propellant charge according to claim 1, wherein the propellant powder body contains a porous propellant cemented with organic binder which burns without leaving a residue.

8. A stud driving tool containing the propellant charge of claim I.

9. The propellant charge of claim I, wherein said recess is centrally located within and extends through said body of propellant powder. 

2. The propellant charge of claim 1, whrein a powder foil covers the recess To prevent the primer substance from inadvertently dropping out of the propellant powder body.
 3. The propellant charge of claim 1, wherein a varnish coating is provided at the end face of the charge.
 4. The propellant charge according to claim 1, wherein the percussion-sensitive primer substance contains an intimate mixture of tetrazene and nitrocellulose.
 5. The propellant charge of claim 1, wherein the propellant powder body contains non-gelantinized, highly compacted nitrocellulose.
 6. The propellant charge according to claim 1, wherein the propellant powder body contains an extruded a gelantinized propellant.
 7. The propellant charge according to claim 1, wherein the propellant powder body contains a porous propellant cemented with organic binder which burns without leaving a residue.
 8. A stud driving tool containing the propellant charge of claim
 9. The propellant charge of claim 1, wherein said recess is centrally located within and extends through said body of propellant powder. 